Uranium purification as complexes of esters of trifluoroacetoacetic acid



Patented Oct. 14, 1952 ED PATENT (J -121 2.614413 URANIUlVF PillfiFfC ATloN As COMPLEXES? OF Es'rEns oF som TRIFLUOROACETOAOETIC Herman-111,, Schlesinger; Chicago, Ill., and HerbeIrtTCIBrown;.Detroit, Mich., assignors to the United statesior America as represented by the UhitedSta'tesAtomic Energy Commission bro-Drawing- Application June 5, 1946;. SerialNo. 674 650 wherein R1 may be alkyl, cycloalkyfofr'aralRyL and'R; isa fluoro substituted"alkylgroup'; In'fsu'ch.

compounds men-own n+ isep erenuy linked by a covalent bond to the enolic group of the diketone and also bya coordinatebondtdthe other ketone group. I

In accordance with" the present invention'it has been 'found'th'at complexes of the above described class may be prepared by reacting'aqueous solutions of uranium compounds capable of supplying ionic uranium preferably in the tetra or hexavalent state with a fiuoro substituted beta keto ester. A per cent NaOH solution is preferably added to the aqueous solution of uranium in tetravalent or hexavalent state and the fluoro substituted beta keto ester to produce a second liquid layer comprising the complex. In this connection it should be noted that the reaction mixture need not necessarily be alkaline for the reaction to proceed; however, in general it has been found that more satisfactory results are obtainable when the reaction is efiected in the presence of a suit- 2? li'exylalcohol. xylene; and ethyl ether? Thewater immiscible organic solvents used iri ulepreeess of the present invention extract the uranium organic complexes from aqueous solutions either by actual solution in the solvent or by preferential wetting of the solvent. In the'case of preferential wetting, the uranium complex may appear in the organic solvent as a suspension or precipitate.-

As examplesof suitablebeta keto esters-theremay be mentioned" benzyl trifluoroacetylacetatee cyclohexyl trifiuoroacetylacetate rpropyltrifiuoro-' acetylaceta'teand the-likes; I p

The compounds. or complexes :herein des'cribed are-stable colored compositions -probably of the chelate-type.= Due to their; extreme stability they? are especially valuablein the recovery" of uranium from solutions thereof which contain impurities commonlyassociatedtherewith. They are gener ally soluble "in the common organic" solventsand exhibit relatively high volatilities compared with other chelatedcomplexes:-- They; may therefore also-be used to"- advantage in-p'rocesses employing vapor'phaseop'erations;E Since mostoftheseconfipositions are highly colored, they may be" used asdyesor pigments.-

The present inventionis illustratedbythe fol lowing :example able base. The oily complex is washed with water by decantation whereby it solidifies. The solidified complex may be separated by filtration or other convenient means and washed with water. It is best purified by sublimation in vacuo, to produce a greenish solid.

In carrying out the invention uranium solutions of the. type contemplated herein are contacted with a fiuoro substituted beta keto ester, preferably ethyl trifiuoroacetoacetate, and the mixture is made alkaline by the addition of a 10 percent NaOH solution to form water insoluble complexes such as herein described. These complexes are then precipitated or extracted with a solvent.

Suitable solvents include chloroform, benzene, ethyl acetate, carbon tetrachloride, aniline, n-

Efcamiile An aqueous solution of uranous chloride was added to a slight excess of ethyl trifiuoroacetylacetate and the mixture stirred at room temperature. A second liquid phase was produced by the addition of a 10 per cent sodium hydroxide solution thereto. When the oily liquid complex was washed with water by decantation, it solidified. On sublimation in vacuo the product distilled to form a greenish white solid condensate, uranous tetraethyl trifiuoroacetoacetate, having the probable formula U(CF3COCHCO2Et) 4, and melting at 61 C. Analysis for C24H24F12012U2 U, Calcd; 24.48 per cent. Found; 24.46 per cent.

Although the present invention has been described with reference to specific details of certain embodiments thereof, it is not intended that such details shall be regarded as limitations except in so far as included in the accompanying claims.

What is claimed is:

1. A complex of uranium having the general structure wherein X is selected from the group consisting 2. A complex of hexavalent uranium having the general structure C-R 2 wherein R1 is a member from the group consisting of alkyl, cycloalkyl and aralkyl radicals and R is a trifluoromethyl radical.

3. A complex of tetravalent uranium having the general structure wherein R1 is a member from the group consisting of alkyl, cyc1oalkyl and aralkyl radicals and R is a trifiuoromethyl radical.

4. Uranium tetra (ethyl trifiuoroacetoacetate) 5. A method for separating uranium from impurities commonly associated therewith which comprises adding to an aqueous solution containing uranium values and said impurities an ester of trifluoroacetoacetic acid, said ester having the formula CF3COCH2COOR1 wherein R1 is a member from the group consisting of alkyl, cycloalkyl and aralkyl radicals and separating the resultant uranium complex.

6. The process of claim 5 wherein the ester of trifluoroacetoacetic acid is ethyl trifluoroacetoacetate.

'7. A method for separating uranium from impurities commonly associated therewith which comprises adding to an aqueous solution containing uranium values and said impurities an ester 4 of trifluoroacetoacetic acid, said ester having the formula CF3-COCH2COOR1 wherein R1 is a member from the group I consisting of alkyl, cycloalkyl and aralkyl radicals, thereafter contacting the aqueous solution with an organic solvent, and separating the resultant aqueous phase and organic extract phase containing a uranium complex.

8. The process of claim 7 in which the organic solvent is chloroform.

9. The process of claim 7 in which the organic solvent is an aromatic hydrocarbon.

10. The process of claim 7 in which the solvent is benzene.

11. I The process of claim 7 in which the solvent is xylene.

12. The process of claim 7 in which the organic solvent is ethyl ether.

. HERMANN I. SCHLESINGER.

HERBERT 0. BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

Transactions, vol. 103, page 86 (1913) Centralblatt, vol. 1927, I, pages 1286-1287. slgugden, Jour. Chem. Soc. (London), 1929, page VVhitmore, Organic Chemistry, pages431 and 443 (1937), published by D. Van Nostrand Company, New York. 

1. A COMPLEX OF URANIUM HAVING THE GENERAL STRUCTURE 